A rotating timing drive in an internal combustion engine, with a camshaft and on chain or belt and sprockets which are driven by the chain or belt, can often vibrate at its resonant frequency. Such vibrations can impose very substantial loads on the chain, or belt, used to drive the camshaft with resultant excessive wear or premature failure of the camshaft drive elements. To avoid such problems, it is known to mount a device, usually called a camshaft damper or a tuned absorber, on the rotating camshaft at a location near the camshaft drive sprocket or pulley and external to the engine block.
A typical camshaft damper of a type heretofore known includes an inner hub that is attached to the camshaft to be rotatable with the camshaft, a ring in and with which the inner hub rotates but is free to slightly oscillate with respect thereto, and a damping, elastomeric fluid that cushions the relative oscillating movement between the inner hub and the ring, which occurs as a result of the tendency of the camshaft to periodically speed up and then slow down in reaction to the torque pulses it experiences during normal service. These torque pulses lead to vibrations, which are especially large when the camshaft speed of rotation is at its resonant frequency. Such a damper has the effect of changing the amplitude of oscillation of the vibration of the camshaft when rotating at its resonant frequency by introducing a vibration that is 180.degree. out of phase with that of the timing drive.